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Refinishing a .45 ACP Conversion Cylinder with Brownells Dicropan IM®
by Roy Seifert

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Disclaimer:  This article is for entertainment only and is not to be used in lieu of a qualified gunsmith.  Please defer all firearms work to a qualified gunsmith.  Any loads mentioned in this article are my loads for my guns and have been carefully worked up using established guidelines and special tools.  The author assumes no responsibility or liability for use of these loads, or use or misuse of this article.  Please note that I am not a professional gunsmith, just a shooting enthusiast and hobbyist, as well as a tinkerer.  This article explains work that I performed to my guns without the assistance of a qualified gunsmith.  Some procedures described in this article require special tools and cannot/should not be performed without them.

Warning:  Disassembling and tinkering with your firearm may void the warranty.  I claim no responsibility for use or misuse of this article.  Again, this article is for entertainment purposes only!

Tools and firearms are the trademark/service mark or registered trademark of their respective manufacturers.


Cylinder As Received (left), Milled and Fitted (right)

I recently purchased two Ruger ,45 ACP conversion cylinders that I found on ebay that came from old-model Ruger Blackhawks.  I fitted these cylinders to my old model Ruger Vaqueros, refer to my article Fitting a .45 ACP Conversion Cylinder.  One of the cylinders was pristine and well cared for; the other was dirty and had rusted. 

Many years ago Ruger would provide their extra cylinders in a red felt bag; the spare cylinder for my Single-Six liberty gun had one.  The problem with these bags was that they absorbed moisture.  Most people never removed the spare cylinder from the bag so eventually the cylinder developed rust as you can see from the above photo.  I also milled the rear face of this cylinder to match the second cylinder so a lot of bare metal was exposed.

If you read my articles you know I am a big fan of cold-bluing.  I have done complete receivers with cold blue solutions and they have come out looking very nice.  This time I wanted to try a different process using Brownell’s Dicropan IM®.  Rather than using hot bluing salts and a single dip process, Dicropan IM is a slower rust-bluing process that requires multiple repeat dipping and carding.  I remembered reading about this process in the October, 2011 issue of American GunSmith and wanted to try it out.[1]


Brownells sells a complete Dicropan IM bluing kit #082-905-105 but I already had most of the components, so I purchased just what I needed; one quart of Dicropan IM #082-008-032, 400-grit polishing compound #080-505-400, and a soft stainless-steel wire wheel #360-164-631.  The wire wheel is used to brush off the surface rust caused by the rust-bluing process.  This brushing is called “carding”.  The Dicropan IM instructions say to use degreased steel wool for the carding process, but the wire wheel will help me card the rear face of the cylinder.  I degreased two pads of 000 steel wool by unrolling a small piece and soaking it in TCE.  I then dried the pad with a paper towel.

I also needed a means of cleaning and degreasing the cylinder, a pot of boiling water, and a method for suspending the cylinder in the boiling water.  I already had Brownells TCE #083-060-032 for cleaning and degreasing, and my wife purchased a cast-iron pot at Goodwill that was deep enough to submerge the cylinder so I was pretty much ready to go.

Polishing and Removing Rust
As with all forms of finish, preparation is everything!  As you can see from the first photo the cylinder had some bad rust spots.  Where ever there was rust a pit existed because rust is a corrosive process which eats away metal.  Why does rust occur on a blued metal surface?  Bluing is a process in which steel is only partially protected against rust with a passive outer-coating of corrosion, and is named after the blue-black appearance of the finish.  Gun bluing is an electrochemical conversion passive coating resulting from an oxidizing chemical reaction with iron on the surface.  This process forms magnetite (Fe3O4), the black oxide of iron.  Black oxide provides only minimal protection against rust, which is why blued firearms must also be treated with a water-displacing oil to reduce wetting and the galvanic action that causes rust; the orange iron-oxide (Fe2O3).  As mentioned before, rust is corrosive; it eats away the base metal and leaves pits.  I wanted the cylinder to be polished and smooth like it came from the factory so first I had to polish out the rust and pits.


I installed a 1/4-20 threaded rod through the pivot hole and held it in place with a nut and washer on either end.  This rod allowed me to secure the cylinder for polishing.


I installed one end of the threaded rod into my padded vise, and used strips of 220-grit, then 400-grit wet/dry sand paper and “shoe-shined” the cylinder.  When one area of the cylinder became smooth and any pits were removed, I rotated the cylinder to work on another area.  I polished completely around the cylinder until it was completely smooth and most of the pits were removed.  I couldn’t remove all of the pits because some of them were very deep and I didn’t want to remove too much metal.


I installed a felt buffing wheel onto a drill and coated the wheel with the 400-grit Polish-O-Ray® compound and finished polishing the cylinder.  The instructions that came with the Dicropan IM recommended use of this product.



After the cylinder was polished I followed the Dicropan IM instructions.  First I completely degreased the cylinder with Brownells TCE #083-060-032, then I suspended the cleaned and degreased cylinder in a pot of boiling water for 5 minutes.  I drilled a hole in a flat piece of wood to prevent the cylinder from tipping over in the pot.  At the end of the 5 minutes I removed the cylinder from the water and shook off any excess water.  The cylinder was so hot that most of the water evaporated.  I used a pad of degreased 000 steel wool to remove any surface rust that appeared, then used a large swab to coat the cylinder with the Dicropan IM.  The exposed metal immediately turned dark black.


I liberally applied the Dicropan IM for 60 seconds, then immersed the cylinder into the boiling water for another 15 minutes.  I again removed the cylinder and shook off the excess water and allowed it to air dry.  The cylinder had a thick, orange-colored coating that I carded off with the degreased steel wool.  I threw away this steel wool and the first swab.  After carding the cylinder was a shiny light blue/black in color.  With Dicropan IM, the more applications, the darker the bluing will become.


I applied 12 more coats of Dicropan IM.  After applying each coat I boiled the cylinder for 5 minutes, removed it from the water, shook off the excess water, and allowed it to air dry.  After the cylinder dried it had a white coating which I carded off with a second degreased pad of 000 steel wool.  It took 9 coats before the cylinder started to take on a darker color, so I did four more applications to get the nice dark color I was looking for.  It looks just a little splotchy in the above photo, but the instructions state this will even out once the bluing cures overnight.


I soaked the cylinder in a water-displacing oil overnight to allow the bluing to cure.  The above photo shows the result.  The only way I could tell the Dicropan IM blued cylinder from the factory blued cylinder was the newly finished cylinder did not have a drag ring caused by the cylinder latch.

Although the Dicropan IM bluing process takes awhile I am very pleased with the results.  It seemed to be very durable; carding with steel wool did not make it come off, and the deep blue-black finish matched the factory finish. 

Hmm, now what else can I finish with Dicropan IM?  The receiver for my 1947 Marlin 39A had a lot of surface rust and I tried to cold-blue it but it didn’t come out very well, so I think I’ll refinish it with Dicropan IM.  Literally, all you need to perform a professional bluing job at home are a few simple supplies and a pot of boiling water.  Who’d of guessed it? 

A special thanks to Paul Mazan for his article in American GunSmith which pointed me in the right direction.  If you would like a subscription to American GunSmith you can contact them at or call them at 1-800-829-5119.

[1] Paul Mazan, “Small Shop Bluing With Brownells Dicropan IM,” American GunSmith, Vol. XXVI, No. 10 (October 2011): 9.



   © Copyright 2014 Roy Seifert.